Users can set up their company's domain in landing page site domain settings so that the landing pages sites/forms are in line with their own company's domain branding. However, there are some limitations to be aware of when the company's domain is set up in landing page site Domain Settings.
External form post code that has the same domain as the landing page, causes your contacts' anonymous data to not be known once they submit the form.
Contact Insight does not reflect the form submission, and any other site/page views or events do not get associated to the contact. It is highly recommended to not use external form post code from a landing pages site that possesses the same domain as the company website where the form is to be embedded.